npm is the package manager for the Node JavaScript platform. It puts modules in place so that node can find them, and manages dependency conflicts intelligently.

It is extremely configurable to support a wide variety of use cases. Most commonly, it is used to publish, discover, install, and develop node programs.

However, as HuangLao all ready stated:

by HuangLao » 2017-11-02 12:35Looks like npm is only in Sid and Jessie:

There is nothing shown for Debian Buster , I don't think it has been released yet, maybe that has something to do with it, but since it is in "SID", looks like there must be plans, still in development.

But it is available, most people with servers are still using Debian Jessieor even older Debian versions for servers. Debian testing and SID are not at all intended for use as a production server. Also, I can't see why this would be needed on a server any way.